problem with ground noise through sub

[zj zack]

so yesterday i went to lock my doors on my 1995 jeep grand cherokee and my subs hit when i pushed the lock button so today i started looking into it and when i grabbed my ground it made noise so i moved my ground directly to the ground on my secondary optima battery and after holding it there for like 5 sec the subs started vibrating idk what the deal is anywhere i ground it after a couple seconds the subs start vibrating any help would be appreciated